UP to a million people will take part in a synchronised toilet flush in an attempt to unblock sewers in Zimbabwe.Authorities in Bulawayo - the country’s second-largest city - have appealed to residents to flush their toilets at 7.30pm on Monday to clear built-up waste. Water is rationed in the city for up to 72 hours each week, which has led to waste accumulating in the sewer network.The city’s mayor, Thaba Moyo, said the mass flush will become a weekly event.“We are going to have a big flush every Monday to push all the waste that would have accumulated during the water rationing. “It means everybody has to flush their toilet at the stipulated time which will be 7.30pm. “This is done to prevent any sewer blockages as we anticipate longer periods without water in the sewer system.” He said the idea of the synchronised flush was suggested by the city’s chief engineer. “We are urging residents to bear with us as this is nobody’s fault. “It’s a national problem. Most cities are having water shortages, and we are hoping that the supplies will last until the rainy season and pray that we have good rains.” –SNPoor sanitation has caused numerous disease outbreaks in Zimbabwe in recent years.Last October, more than 6,000 cases of diarrhoea were reported in the southern towns of Masvingo and Kadoma, with children the worst affected.Four years ago more than 4,000 people died of cholera during an outbreak that affected nearly 100,000 people.